This project is concerned with investigating: i) the diffusion into the tissues of the eye and of the orbit of electron opaque tracers introduced into the anterior chamber at controlled values of intraocular pressure; ii) the movement of electron opaque tracers from the vitreous body into the vessels of the retina and optic nerve. A necessary corollary of this study is the analyis with conventional electron microscopy of the morphology of the retinal vascular tree and a freeze-fracture analysis of the endothelial junctions; iii) the morphological aspects of the glaucoma induced by the introduction of alpha chymotrypsin into the posterior chamber. Animals of choice are rabbits and macaque monkeys. The precise knowledge of the anatomical mechanisms which regulate the intraocular pressure is necessary for a better understanding of the pathogenesis of glaucomas and for devising new pharmacological methods for their control.